aorta - the largest artery in the body and the primary blood vessel which carries oxygenated blood out of the heart to the rest of the body.

aortic arch - the curved portion of the aorta (the large blood vessel that carries oxygen-rich blood away from the heart to the body).

aortic regurgitation - backwards leakage of blood from the aorta, through a weakened aortic valve, and into the left ventricle, resulting in stress in the left heart and inadequate blood flow to the body.

aortic stenosis - narrowing of the opening of the aortic valve (the valve that regulates blood flow from the left ventricle into the aorta).

aortic valve - the valve that regulates blood flow from the heart into the aorta.

arteriosclerosis - commonly called "hardening of the arteries;" a variety of conditions caused by fatty or calcium deposits in the artery walls causing them to thicken.

artery - a blood vessel that carries oxygenated blood away from the heart to the body.

asplenia - absence of the spleen, either from improper development before birth, or due to the surgical removal of the spleen resulting from injury or disease.

asymmetry - lacking symmetry; parts of the body are unequal in shape or size.

atresia - inadequate development of an organ or part of an organ during pregnancy.

atrial fibrillation - a very fast and irregular beating of the atria (the upper two chambers of the heart).

atrial flutter - a very fast beating of the atria (the upper two chambers of the heart).

atrial septal defect (ASD) - a hole in the wall between the right and left atria (the two upper chambers of the heart).

atrial septum - the wall between the right and left atria (the two upper chambers of the heart).

atrioventricular block - an interruption of the electrical signal between the atria and the ventricles.

atrioventricular canal - refers to a congenital heart defect involving an opening low in the atrial septum, an opening high in the ventricular septum, and abnormal development of the mitral and/or tricuspid valves.

atrioventricular (AV) node - a cluster of cells between the atria and ventricles that regulate the electrical current.

cardioversion - the procedure of applying electrical shock to the chest to change an abnormal heartbeat into a normal one.

carotid artery - the major arteries in the neck that supply blood to the brain.

catheter - a small, thin tube; may refer to a tube used during a cardiac catheterization procedure to inject dye, obtain blood samples, and measure pressures inside the heart; may also refer to a flexible tube used to drain fluid from or inject into the body.

cholesterol - a substance normally made by the body, but also found in foods from animal sources, like beef, eggs, and butter. Too much cholesterol in the body can lead to narrowing and blockage of the arteries, especially those that feed the heart and keep it healthy. High cholesterol can also cause the formation of gallstones. Ideally, blood cholesterol levels should be less than 200mg/dL.

cineangiography - the procedure of taking moving pictures to show the passage of dye through blood vessels.

circulatory system - pertaining to the heart and blood vessels, and the circulation of blood.

closed heart surgery - an operation that repairs problems involving the blood vessels attached to the heart without the use of the heart-lung bypass machine.

coarctation of the aorta - a congenital heart defect that results in narrowing of the aorta.

collateral vessels - new blood vessels that are created by the body to provide extra blood flow to an area when the blood vessel(s) that are already there are too small, narrowed, or blocked.

computed tomography scan (Also called a CT or CAT scan.) - a diagnostic imaging procedure that uses a combination of x-rays and computer technology to produce horizontal, or axial, images (often called slices) of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than general x-rays.

conduction system - the electrical system inside the heart that stimulates the heart to beat.

congenital - present at birth.

congenital heart defect - a heart problem present at birth, caused by improper development of the heart during fetal development.

congenital heart disease - see congenital heart defect.

congestive heart failure - a condition in which the heart cannot pump out all of the blood that enters it, which leads to an accumulation of blood in the vessels leading to the heart and fluid in the body tissues. Excess blood in the pulmonary (lung) blood vessels can also occur, leading to fluid accumulation in the lungs.

coronal suture - the joining line (suture) between the frontal and parietal bones of the skull that crosses the top of the skull from temple to temple.

coronary arteries - two arteries that come from the aorta to provide blood to the heart muscle.

defibrillator - an electronic device used to establish normal heartbeat.

dextrocardia - a heart that is "flipped over," so that the structures that are normally on the right side of the chest are on the left, and vice versa. The arteries and veins are connected correctly; occurs due to an abnormality in heart development during pregnancy.

diastole - the time during each heartbeat when the ventricles are at rest, filling with blood and not pumping.

diastolic blood pressure - the lowest blood pressure measure in the arteries, which occurs between heartbeats.

DiGeorge syndrome (Also known as Shprintzen, velo-cardio-facial, and 22q11.2 deletion syndrome.) - A genetic disease caused by a missing piece of chromosome material on chromosome #22 that results in many different health problems, and affects the normal fetal development of the heart, thymus, and parathyroid glands.

diuretic - a medication that helps the kidneys to remove excess fluids from the body, lowering blood pressure as well as decreasing edema (swelling).

double outlet right ventricle - a congenital heart defect in which both the aorta and the pulmonary artery are connected to the right ventricle.

Down syndrome (Also called Trisomy 21.) - A combination of birth defects caused by the presence of an extra #21 chromosome in each cell of the body. Many children with Down syndrome also have congenital heart disease - usually atrioventricular canal defect.

ductus arteriosus - a connection between the aorta and the pulmonary artery that is necessary in fetal life, but becomes unnecessary after birth.

Ebstein's anomaly - Abnormal development of the tricuspid valve during pregnancy, causing an abnormally positioned valve that does not open easily (stenosis) and allows backflow of blood from the right ventricle into the right atrium (regurgitation).

echocardiogram (echo) - a procedure that evaluates the structure and function of the heart by using sound waves recorded on an electronic sensor which produce a moving picture of the heart and heart valves.

edema - swelling due to the buildup of fluid.

effusion - a collection of fluid in a closed cavity.

Eisenmenger's syndrome - severe pulmonary vascular disease and pulmonary hypertension (high blood pressure in the blood vessels of the lungs) due to prolonged left to right shunting of blood in the heart, now with a reversal of the shunt from right to left.

ejection fraction - the measurement of the amount of blood pumped out of the ventricles.

electrocardiogram (ECG or EKG) - a test that records the electrical activity of the heart, shows abnormal rhythms (arrhythmias or dysrhythmias), and detects heart muscle damage.

electrophysiological study (EPS) - a cardiac catheterization to study electrical current in patients who have arrhythmias.

endocarditis - a bacterial infection of the valves and interior surfaces of the heart.

endocardium - the membrane that covers the inside surface of the heart.

end-to-end anastomosis - surgical connection of two segments of blood vessel by stitching the open end of one segment to the open end of another segment.

enlarged heart - a condition of the heart in which it is larger than normal.

epicardium - the outermost aspect of the heart.

erythrocytosis - an abnormal increase in the number of red blood cells in the blood due to chronic lack of oxygen.

exercise electrocardiogram (stress ECG or stress EKG) - a test to assess the cardiac rhythm and function by having the child exercise on a treadmill or bicycle.

failure to thrive - failure to grow and gain weight; often due to increased energy expenditure with congenital heart disease.

fibrillation - rapid, irregular, and weak contractions of the heart muscles. Atrial fibrillation refers to rapid irregular and weak contractions of the atria with correspondingly rapid and irregular contractions of the ventricles, often resulting in palpitations. Ventricular fibrillation refers to rapid, irregular, and weak contractions of the ventricles, resulting in no effective blood flow out of the heart (cardiac arrest).

fluoroscopy - an x-ray procedure that takes continuous pictures to evaluate moving structures within the body, such as the heart.

flutter - rapid but regular contractions of the right and left atrium. This results in correspondingly rapid and regular contractions of the ventricles, often faster than normal, leading to palpitations.

Fontan procedure - A surgical procedure performed to repair heart defects in which only one ventricle is functional. It connects the inferior vena cava to the pulmonary artery and also connects the superior vena cava to the pulmonary artery, allowing oxygen-poor (blue) blood from the body to flow into the lungs passively, without the use of the right heart to pump this blood into the lungs.

foramen ovale - a hole between the right and left atria, present in all unborn children, that remains open after birth for variable periods of time.

Glenn shunt - A surgical connection between the superior vena cava and the right pulmonary artery, allowing oxygen-poor (blue) blood to flow into the lungs. This represents the first half of a Fontan procedure.

heart attack (Also called myocardial infarction.) - occurs when one of more regions of the heart muscle experience a severe or prolonged decrease in oxygen supply caused by a blocked blood flow to the heart muscle.

heart block - interrupted electrical impulse to heart muscles.

heart-lung bypass machine - a machine that performs for the heart and lungs during open heart surgery.

heart valve prolapse - a condition of the heart valve in which it is partially open when it should be closed.

high blood pressure (Also called hypertension.) - blood pressure that is above the normal range.

high density lipoprotein (HDL) - the "good" cholesterol that promotes breakdown and removal of cholesterol from the body.

Holter monitor - A portable EKG machine worn for a 24-hour period or longer to evaluate irregular, fast, or slow heart rhythms while engaging in normal activities.

homograft - any tissue that is taken from a cadaver donor (another human being who has passed away). This tissue is used to replace missing or defective tissue in the body. It may be a blood vessel, most often the pulmonary artery or aorta, or a tissue valve, either the pulmonary valve or the aortic valve.

left atrium - the upper left-hand chamber of the heart. It receives oxygen-rich (red) blood from the lungs via the four pulmonary veins, and then sends this blood to the left ventricle.

left ventricle - the lower left-hand chamber of the heart. It receives oxygen-rich (red) blood from the left atrium and pumps it into the aorta, which takes the blood to the body. The left ventricle must be strong and muscular in order to pump enough blood to the body to meet its requirements.

lesion - an injury or wound.

lipid - a fatty substance in the blood.

lipoproteins - transporters of fatty substances in the blood.

low density lipoprotein (LDL) - the primary cholesterol-carrying substance in the body. In large amounts, it accumulates inside arteries.

magnetic resonance imaging (MRI) - a diagnostic procedure that uses a combination of large magnets, radiofrequencies, and a computer to produce detailed images of organs and structures within the body.

Marfan syndrome - A genetic disorder which affects the connective tissue of the body. It causes dilation of blood vessels and abnormalities of cardiac valves.

mechanical valve - an artificial valve used to replace a diseased or defective valve, most often the aortic valve.

median sternotomy - an incision in the center of the chest, from the top to the bottom of the breastbone, used for many congenital heart defect repair surgeries.

mitral valve - the valve that controls blood flow between the left atrium and left ventricle in the heart.

mitral valve prolapse - an abnormality of the valve between the left atrium and left ventricle of the heart that causes backward flow of blood from the left ventricle into the left atrium.

murmur - a blowing or rasping sound heard while listening to the heart that may or may not indicate problems within the heart or circulatory system.

myocardial infarction (Also called heart attack.) - occurs when one of more regions of the heart muscle experience a severe or prolonged decrease in oxygen supply caused by a blocked blood flow to the heart muscle.

occluded artery - an artery that is narrowed by plaque that impedes blood flow.

open heart surgery - surgery that involves opening the chest and heart while a heart-lung machine performs for the heart and lungs during the operation.

oxygen desaturation - insufficient amounts of oxygen in the bloodstream. Desaturation can occur when oxygen-poor (blue) blood from the right side of the heart circulation mixes with oxygen-rich (red) blood in the left side of the heart circulation and goes to the body. Normal oxygen saturation in the arteries is 95 to 100 percent.

oxygen saturation - the extent to which the hemoglobin is saturated with oxygen. (Hemoglobin is an element in the bloodstream that binds with oxygen and carries it to the organs and tissues of the body.) A normal oxygen saturation of the blood leaving the heart to the body is 95 to 100 percent. The oxygen saturation of the blood returning to the heart after delivering oxygen to the body is 75 percent or less.

pacemaker - an electronic device that is surgically placed in the patient's body and connected to the heart to regulate the heartbeat.

palpitation - a sensation of rapid heartbeats.

patent - open.

patent ductus arteriosus (PDA) - a blood vessel present in all infants that usually closes shortly after birth. It connects the aorta to the pulmonary artery. When it remains open, it allows extra blood to pass through from the aorta to the lungs. See ductus arteriosus.

patent foramen ovale - an opening in the atrial septum (wall between the right and left atria) that is present in all infants, but which usually closes shortly after birth. When it remains open, it allows extra blood to pass through the opening from the left atrium to the right atrium. See foramen ovale.

pericardial effusion - a build up of excess fluid in-between the heart and the membrane that surrounds it, often due to inflammation.

pericardiocentesis - a diagnostic procedure that uses a needle to draw fluid from the pericardium.

pericarditis - an inflammation or infection of the sac which surrounds the heart.

pericardium - the membrane that surrounds the heart.

plaque - deposits of fat or other substances attached to the artery wall.

platelets - cells found in the blood that assist in clotting.

polyunsaturated fat - a type of fat found in vegetable oils and margarines that does not appear to raise blood cholesterol levels.

post-pericardiotomy syndrome - a build up of excess fluid in-between the heart and the membrane that surrounds it, often due to inflammation after open heart surgery. ("Post" means after, and "pericardiotomy" means opening the membrane around the heart for open heart surgery.)

premature atrial contraction (PAC) - an early heartbeat started by the atria.

premature ventricular contraction (PVC) - an early heartbeat started by the ventricles.

prophylaxis - prevention.

prostaglandin E1 - an intravenous medication used to keep a patent ductus arteriosus from closing and preserve blood flow to the lungs.

pulmonary - pertaining to the lungs and respiratory system.

pulmonary artery - the blood vessel connecting the right ventricle to the lungs, allowing oxygen-poor (blue) blood to receive oxygen.

pulmonary edema - a condition in which there is fluid accumulation in the lungs caused by an incorrectly functioning heart.

pulmonary valve - the heart valve located between the right ventricle and the pulmonary artery that controls blood flow to the lungs.

pulmonary vein - the vessel that carries oxygenated blood from the lungs to the left side of the heart.

pulse oximeter - a device that measures the amount of oxygen in the blood. Normal oxygen saturation in the arteries is 95 to 100 percent.

rheumatic fever - a disease caused by a strep infection that may damage the heart valves.

right atrium - the upper right chamber of the heart, which receives oxygen-poor (blue) blood from the body and sends it to the right ventricle.

right ventricle - the lower right chamber of the heart, which receives oxygen-poor (blue) blood from the right atrium and sends it to the pulmonary artery.

risk factor - a condition, element, or activity that may adversely affect the heart.

Ross procedure - A surgical procedure performed to repair aortic stenosis. The child's own pulmonary valve and base of the pulmonary artery (autograft) replace the defective aorta, while a homograft (blood vessel from a tissue donor) replaces the pulmonary valve and base of the pulmonary artery.

rubella - an illness that can cause birth defects, including congenital heart disease, if a woman contracts it for the first time during pregnancy; can be prevented by immunization with the MMR vaccine.

saturated fat - fat that is found in foods from animal meats and skin, dairy products, and some vegetables. Saturated fats are usually solid at room temperatures and can increase LDL levels.

scaphocephaly - a form of craniosynostosis that results in a long, narrow head. Scaphocephaly is an early fusion of the sagittal suture. This suture runs front to back, down the middle of the top of the head.

septal defect - a hole in the wall between the atria or the ventricles (upper or lower heart chambers).

septum - the muscle wall between the atria or ventricles (upper or lower heart chambers).

shunt - a connector to allow blood flow between two locations.

sinus node - the cells that produce the electrical impulses that cause the heart to contract.

sinus rhythm - a normal heart rhythm in which each heartbeat originates in the sinus node, and proceeds through the rest of the electrical conduction system normally.

sinus tachycardia - a heart rhythm that originates in the sinus node and proceeds through the rest of the electrical conduction system, but is faster than normal.

sphygmomanometer - an instrument used to measure blood pressure.

stent - a device implanted in a vessel used to help keep it open.

stenosis - narrowing or constriction of a blood vessel or valve in the heart.

sternotomy - a surgical incision made in the breastbone.

sternum - the breastbone.

stethoscope - an instrument used to listen to the heart and other sounds in the body.

tamponade - an emergency situation that occurs when blood or fluid fills the pericardial sac surrounding the heart, preventing the heart from beating effectively.

telemetry unit - a small box with wires attached to EKG patches on the chest; used to send information about the heartbeat via radio transmission to healthcare professionals for evaluation.

tetralogy of Fallot (TOF) - a group of congenital heart defects, including a ventricular septal defect, obstruction to blood flow out of the right ventricle to the lungs, and an aorta that is shifted to the right. Enlargement of the right ventricle occurs as the right ventricle copes with obstruction to blood flow.

thoracotomy - an incision made on the right or left side of the chest between the ribs, in order to access the heart or lungs during surgery.

trans fat - vegetable oil that has been treated with hydrogen in order to make it more solid and give it a longer shelf life.

transesophageal echocardiography (TEE) - a diagnostic test that uses a long tube guided into the mouth, throat, and esophagus to evaluate the structures inside the heart with sound waves.

transplantation - replacing a damaged organ with one from a donor.

transposition of the great arteries (Also called transposition of the great vessels.) - a congenital heart defect involving abnormal development of the great arteries (the aorta and the pulmonary artery) during the time the heart is forming prior to birth. The aorta ends up being connected to the right ventricle, and the pulmonary artery is connected to the left ventricle, which is the opposite of how they are normally connected.

tricuspid atresia - a congenital heart defect in which the tricuspid valve and right ventricle do not develop properly, preventing oxygen-poor (blue) blood from reaching the lungs via its normal pathway.

tricuspid valve - the heart valve that controls blood flow from the right atrium into the right ventricle.

triglyceride - a fat-like substance found in the blood.

trigonocephaly - a form of craniosynostosis that results in a triangular configuration of the skull. Trigonocephaly is the premature fusion of the two halves of the frontal bones at the metopic suture.

trisomy 21 (Also called Down syndrome.) - the presence of three #21 chromosomes in each cell of the body, rather than the usual pair, which causes the features otherwise known as Down syndrome. Many children with Down syndrome also have congenital heart disease - usually atrioventricular canal defect.

truncus arteriosus - a congenital heart defect involving incomplete separation of the great arteries (the aorta and the pulmonary artery) during the time the heart is forming prior to birth.

ultrasound (Also called sonography.) - a diagnostic imaging technique which uses high-frequency sound waves and a computer to create images of blood vessels, tissues, and organs. Ultrasounds are used to view internal organs as they function, and to assess blood flow through various vessels.

valves - the "doors" between the chambers of the heart that allow blood to move forward and prevent it from moving backward. The heart valves are called tricuspid, pulmonic, mitral, and aortic.

valvuloplasty - surgical repair of a heart valve for relief of incompetence.

vascular - pertaining to blood vessels.

vasodilator - a medication that dilates or widens the opening in a blood vessel.

vasopressor - a medication that raises blood pressure.

vasovagal syndrome - a sudden drop in blood pressure, with or without a decrease in heart rate, that is caused by a dysfunction of the nerves controlling the heart and blood vessels.

vein - a blood vessel that carries blood from the body back into the heart.

ventricle - one of the two pumping chambers of the heart; right ventricle receives oxygen-poor blood from the right atrium and pumps it to the lungs through the pulmonary artery; left ventricle receives oxygen-rich blood from the left atrium and pumps it to the body through the aorta.

ventricular fibrillation - a condition in which the ventricles contract in rapid and unsynchronized rhythms and cannot pump blood into the body.

ventricular septal defect - an abnormal opening in the wall between the right and left ventricles.

ventricular tachycardia - a condition in which the ventricles beat very quickly.